Cell surface receptors are critical for cell signaling and constitute a quarter of all human genes. Despite their importance and abundance, receptor interaction networks remain understudied because of difficulties associated with maintaining membrane proteins in their native conformation and their typically weak interactions. To overcome these challenges, we developed an extracellular vesicle-based method for membrane protein display that enables purification-free and high-throughput detection of receptor-ligand interactions in membranes. We demonstrate that this platform is broadly applicable to a variety of membrane proteins, enabling enhanced detection of extracellular interactions over a wide range of binding affinities. We were able to recapitulate and expand the interactome for prominent members of the B7 family of immunoregulatory proteins such as PD-L1/CD274 and B7-H3/CD276. Moreover, when applied to the orphan cancer-associated fibroblast protein, LRRC15, we identified a membrane-dependent interaction with the tumor stroma marker TEM1/CD248. Furthermore, this platform enabled profiling of cellular receptors for target-expressing as well as endogenous extracellular vesicles. Overall, this study presents a sensitive and easy to use screening platform that bypasses membrane protein purification and enables characterization of interactomes for any cell surface-expressed target of interest in its native state.

Keywords: extracellular vesicle; high-throughput screening; membrane protein; receptor–ligand interaction.

Co-inhibitory B7-CD28 family member proteins negatively regulate T cell responses and are extensively involved in tumor immune evasion. Blockade of classical CTLA-4 (cytotoxic T lymphocyte-associated antigen-4) and PD-1 (programmed cell death protein-1) checkpoint pathways have become the cornerstone of anti-cancer immunotherapy. New inhibitory checkpoint proteins such as B7-H3, B7-H4, and BTLA (B and T lymphocyte attenuator) are being discovered and investigated for their potential in anti-cancer immunotherapy. In addition, soluble forms of these molecules also exist in sera of healthy individuals and elevated levels are found in chronic infections, autoimmune diseases, and cancers. Soluble forms are generated by proteolytic shedding or alternative splicing. Elevated circulating levels of these inhibitory soluble checkpoint molecules in cancer have been correlated with advance stage, metastatic status, and prognosis which underscore their broader involvement in immune regulation. In addition to their potential as biomarker, understanding their mechanism of production, biological activity, and pathological interactions may also pave the way for their clinical use as a therapeutic target. Here we review these aspects of soluble checkpoint molecules and elucidate on their potential for anti-cancer immunotherapy.

Keywords: alternative splice variants (ASV); cancer vaccination (CVax); gene therapy; immune checkpoint blockade (ICB); immunotherapy (IT); soluble immune checkpoints (SIC).

B7-H3 (also known as CD276) is associated with aggressive characteristics in various cancers. Meanwhile, in alveolar rhabdomyosarcoma (ARMS), PAX3-FOXO1 fusion protein is associated with increased aggressiveness and poor prognosis. In the present study, we explored the relationship between PAX3-FOXO1 and B7-H3 and the biological roles of B7-H3 in ARMS. Quantitative real time PCR and flow cytometry revealed that PAX3-FOXO1 knockdown downregulated B7-H3 expression in all the selected cell lines (Rh-30, Rh-41, and Rh-28), suggesting that PAX3-FOXO1 positively regulates B7-H3 expression. Gene expression analysis revealed that various genes and pathways involved in chemotaxis, INF-γ production, and myogenic differentiation were commonly affected by the knockdown of PAX3-FOXO1 and B7-H3. Wound healing and transwell migration assays revealed that both PAX3-FOXO1 and B7-H3 were associated with cell migration. Furthermore, knockdown of PAX3-FOXO1 or B7-H3 induced myogenin expression in all cell lines, although myosin heavy chain induction varied depending on the cellular context. Our results indicate that PAX3-FOXO1 regulates B7-H3 expression and that PAX3-FOXO1 and B7-H3 are commonly associated with multiple pathways related to an aggressive phenotype in ARMS, such as cell migration and myogenic differentiation block.

The content of the soluble form of protein of the key point of immunity B7-H3 (sB7-H3) in the blood plasma of 75 patients with epithelial ovarian cancer before treatment was measured by ELISA. It is known that B7-H3 belongs to the immunoglobulin superfamily (B7 molecule family) and is involved in the regulation of the immune response mediated by T cells. The sB7-H3 concentration correlated with the clinical and morphological parameters of ovarian cancer. The content of sB7-H3 was higher at the later stages of the disease, in the presence of ascites, and in patients with poorly differentiated ovarian cancer. It was revealed that increased plasma content of sB7-H3 in patients with epithelial ovarian cancer is associated with unfavorable prognosis of the disease. Therefore, sB7-H3 can be used as a prognostic marker in ovarian cancer patients.

Keywords: ovarian cancer; sB7-H3; survival.

This study was conducted to describe the association between the genetic variation of the recently identified immune checkpoint molecules B7-H3 and B7-H4, and the susceptibility to ankylosing spondylitis (AS). Two single nucleotide polymorphisms (SNPs) of B7-H3 gene and three SNPs of B7-H4 gene were genotyped in 649 AS patients and 646 age- and sex-matched healthy controls. Allele, genotype frequencies and different inheritance models were performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs), and the demographic and clinical parameters of patients were recorded. Our data indicated that B7-H4 rs10801935 and rs3738414 polymorphisms were correlated with AS susceptibility. In the stratification analyses, the minor A allele and GA genotype of B7-H4 rs3738414 increased the risk of AS in male patients (OR = 1.244, 95%CI = 1.026-1.508; OR = 1.453, 95%CI = 1.120-1.886, respectively). However, the association did not reach statistical significance after Bonferroni correction. Furthermore, haplotype analysis revealed that B7-H4 haplotype block TAG was a risk factor for the onset of AS (OR = 1.190, 95%CI = 1.020-1.389). These findings suggested that B7-H4 gene polymorphism may contribute to AS susceptibility in eastern Chinese Han population.

Keywords: B7-H3; B7-H4; ankylosing spondylitis; haplotype; polymorphisms.

The role of B7-H3 in acute myeloid leukemia (AML) is not fully understood. Two previous studies investigating its expression and significances in AML are partially different. In this study, we aimed to systematically characterize the genomic and immune landscape in AML patients with altered B7-H3 expression using multi-omics data in the public domain. We found significantly increased B7-H3 expression in AML compared to either other hematological malignancies or healthy controls. Clinically, high B7-H3 expression was associated with old age, TP53 mutations, wild-type WT1 and CEBPA, and the M3 and M5 FAB subtypes. Moreover, we observed that increased B7-H3 expression correlated significantly with a poor outcome of AML patients in four independent datasets. Gene set enrichment analysis (GSEA) revealed the enrichment of the "EMT" oncogenic gene signatures in high B7-H3 expressers. Further investigation suggested that B7-H3 was more likely to be associated with immune-suppressive cells (macrophages, neutrophils, dendritic cells, and Th17 cells). B7-H3 was also positively associated with a number of checkpoint genes, such as VISTA (B7-H5), CD80 (B7-1), CD86 (B7-2), and CD70. In summary, we uncovered distinct genomic and immunologic features associated with B7-H3 expression in AML. This may lead to a better understanding of the molecular mechanisms underlying B7-H3 dysregulation in AML and to the development of novel therapeutic strategies.

Keywords: B7-H3; acute myeloid leukemia; immune checkpoint; prognosis.

Sarcomas are a diverse group of bone and soft tissue tumors that account for over 10% of childhood cancers. Outcomes are particularly poor for children with refractory, relapsed, or metastatic disease. Chimeric antigen receptor T (CAR T) cells are an exciting form of adoptive cell therapy that potentially offers new hope for these children. In early trials, promising outcomes have been achieved in some pediatric patients with sarcoma. However, many children do not derive benefit despite significant expression of the targeted tumor antigen. The success of CAR T cell therapy in sarcomas and other solid tumors is limited by the immunosuppressive tumor microenvironment (TME). In this review, we provide an update of the CAR T cell therapies that are currently being tested in pediatric sarcoma clinical trials, including those targeting tumors that express HER2, NY-ESO, GD2, EGFR, GPC3, B7-H3, and MAGE-A4. We also outline promising new CAR T cells that are in pre-clinical development. Finally, we discuss strategies that are being used to overcome tumor-mediated immunosuppression in solid tumors; these strategies have the potential to improve clinical outcomes of CAR T cell therapy for children with sarcoma.

Keywords: CAR T cells; immunotherapy; sarcoma.

Within the prostate tumor microenvironment (TME) there are complex multi-faceted and dynamic communication occurring between cancer cells and immune cells. Macrophages are key cells which infiltrate and surround tumor cells and are recognized to significantly contribute to tumor resistance and metastases. Our understanding of their function in the TME is commonly based on in vitro and in vivo models, with limited research to confirm these model observations in human prostates. Macrophage infiltration was evaluated within the TME of human prostates after 72 h culture of fresh biopsies samples in the presence of control or enzalutamide. In addition to immunohistochemistry, an optimized protocol for multi-parametric evaluation of cellular surface markers was developed using flow cytometry. Flow cytometry parameters were compared to clinicopathological features. Immunohistochemistry staining for 19 patients with paired samples suggested enzalutamide increased the expression of CD163 relative to CD68 staining. Techniques to validate these results using flow cytometry of dissociated biopsies after 72 h of culture are described. In a second cohort of patients with Gleason grade group ≥ 3 prostate cancer, global macrophage expression of CD163 was unchanged with enzalutamide treatment. However, exploratory analyses of our results using multi-parametric flow cytometry for multiple immunosuppressive macrophage markers suggest subgroup changes as well as novel associations between circulating biomarkers like the neutrophil to lymphocyte ratio (NLR) and immune cell phenotype composition in the prostate TME. Further, we observed an association between B7-H3 expressing tumor-associated macrophages and the presence of intraductal carcinoma. The use of flow cytometry to evaluate ex vivo cultured prostate biopsies fills an important gap in our ability to understand the immune cell composition of the prostate TME. Our results highlight novel associations for further investigation.

Novel therapeutic strategies are needed for the treatment of rhabdomyosarcoma (RMS), the most common soft-tissue sarcoma in children. By using a combination of cell surface proteomics and transcriptomic profiling of RMS and normal muscle, we generated a catalog of targetable cell surface proteins enriched in RMS tumors. Among the top candidates, we identified B7-H3 as the major immunoregulatory molecule expressed by RMS tumors. By using a large cohort of tissue specimens, we demonstrated that B7-H3 is expressed in a majority of RMS tumors while not detected in normal human tissues. Through a deconvolution analysis of the RMS tumor RNA-seq data, we showed that B7-H3-rich tumors are enriched in macrophages M1, NK cells, and depleted in CD8⁺-T cells. Furthermore, in vitro functional assays showed that B7-H3 knockout in RMS tumor cells increases T-cell mediated cytotoxicity. Altogether, our study uncovers new potential targets for the treatment of RMS and provides the first biological insights into the role of B7-H3 in RMS biology, paving the way for the development of next-generation immunotherapies.

Keywords: B7-H3; cell surface proteomics; rhabdomyosarcoma; targeted therapies.

Background: Ferroptosis is the latest-discovered, iron-dependent form of regulated cell death. It has been increasingly recognized that ferroptosis-related genes participate in oncogenesis and development of cancers, including breast cancer (BRCA). Thus, It is important to explore the biofunctions of ferroptosis-related genes in BRCA.

Methods: Transcriptome microarray datasets (GSE22358, GSE9014 and GSE8977, GSE2990 and GSE2034) and TCGA-BRCA were retrieved for analyses. And a variety of computational tools were used to identify the roles and associated biological functions in BRCA.

Results: Two ferroptosis-related genes (AKR1C1 and AKR1C3) were significantly expressed in GSE22358, GSE9014 and GSE8977. Higher expression of AKR1C1 was related with favorable prognosis. TCGA-BRCA further confirmed the expression of AKR1C1 and the prognostic value of AKR1C1. Co-expression analyses showed the most enriched GO term and KEGG pathways were termination of DNA-templated transcription and Fanconi anemia pathway. Subsequently, immunological analyses showed AKR1C1 was significantly associated with various immune infiltration cells; among these, dendritic cells, neutrophils, macrophages were the top three infiltrating cells. Furthermore, AKR1C1 was also associated with multiple immunostimulatory molecules and chemokines, including PD-1, PD-L1, CTLA4, B7-H3, VSIR, IL-6, BTLA, CXCL2, and CCR7. These results indicated the potential roles of AKR1C1 in the immune reaction during the pathogenesis of breast cancer.

Conclusion: This study firstly demonstrated that ferroptosis-related gene, AKR1C1, could be associated with immune microenvironment, thereby influencing the development and prognosis of patient with breast cancer.

Keywords: AKR1C1; breast cancer; ferroptosis; immune infiltration; immune microenvironment.

The pancaner molecule CD276 (B7-H3) is an attractive target for antibody based therapy. We identified from a large (10¹¹) phage-displayed single-chain variable fragment (scFv) library, a fully human antibody, B11, which bound with high avidity (K_D=0.4 nM) to CD276. B11 specifically bound to the V1/V2 domain of CD276 and competed with the antibody 8H9 (Omburtamab). It was used to design an IgG-format bispecific T cell engager B11-BiTE, which was more effective than 8H9-BiTE in 14 different cancer cell lines. B11-BiTE also exhibited strong ADCC/ADCP. Therefore, the fully human B11-BiTE is a promising candidate for treatment of tumors expressing CD276.

Keywords: Bispecific T cell engager (BiTE); CD276 (B7-H3); Fully human antibody; V1/V2 domain.

Background: Glioma is the most frequent brain malignancy presenting very poor prognosis and high recurrence rate. Focal adhesion complexes play pivotal roles in cell migration and act as hubs of several signaling pathways.

Methods: We used bioinformatic databases (CGGA, TCGA, and GEO) and identified a focal adhesion-related differential gene expression (FADG) signature by uniCox and LASSO regression analysis. We calculated the risk score of every patient using the regression coefficient value and expression of each gene. Survival analysis, receiver operating characteristic curve (ROC), principal component analysis (PCA), and stratified analysis were used to validate the FADG signature. Then, we conducted GSEA to identify the signaling pathways related to the FADG signature. Correlation analysis of risk scores between the immune checkpoint was performed. In addition, the correlation of risk scores and genes related with DNA repair was performed. CIBERSORT and ssGSEA were used to explore the tumor microenvironment (TME). A nomogram that involved our FADG signature was also constructed.

Results: In total, 1,726 (528 patients diagnosed with WHO II, 591 WHO III, and 603 WHO IV) cases and 23 normal samples were included in our study. We identified 29 prognosis-related genes in the LASSO analysis and constructed an eight FADG signature. The results from the survival analysis, stratified analysis, ROC curve, and univariate and multivariate regression analysis revealed that the prognosis of the high-risk group was significantly worse than the low-risk group. Correlation analysis between risk score and genes that related with DNA repair showed that the risk score was positively related with BRCA1, BRCA2, RAD51, TGFB1, and TP53. Besides, we found that the signature could predict the prognosis of patients who received radiation therapy. SsGSEA indicated that the high-risk score was positively correlated with the ESTIMATE, immune, and stromal scores but negatively correlated with tumor purity. Notably, patients in the high-risk group had a high infiltration of immunocytes. The correlation analysis revealed that the risk score was positively correlated with B7-H3, CTLA4, LAG3, PD-L1, and TIM3 but inversely correlated with PD-1.

Conclusion: The FADG signature we constructed could provide a sensitive prognostic model for patients with glioma and contribute to improve immunotherapy management guidelines.

Keywords: focal adhesion; glioma; immune checkpoints; prognosis; radiation response; tumor microenvironment.

While their function, as immune checkpoint molecules, is well known, B7-family proteins also function as regulatory molecules in bone remodeling. B7-H3 is a receptor ligand of the B7 family that functions primarily as a negative immune checkpoint. While the regulatory function of B7-H3 in osteoblast differentiation has been established, its role in osteoclast differentiation remains unclear. Here we show that B7-H3 is highly expressed in mature osteoclasts and that B7-H3 deficiency leads to the inhibition of osteoclastogenesis in human osteoclast precursors (OCPs). High-throughput transcriptomic analyses reveal that B7-H3 inhibition upregulates IFN signaling as well as IFN-inducible genes, including IDO. Pharmacological inhibition of type-I IFN and IDO knockdown leads to reversal of B7-H3-deficiency-mediated osteoclastogenesis suppression. Although synovial-fluid macrophages from rheumatoid-arthritis patients express B7-H3, inhibition of B7-H3 does not affect their osteoclastogenesis. Thus, our findings highlight B7-H3 as a physiologic positive regulator of osteoclast differentiation and implicate type-I IFN-IDO signaling as its downstream mechanism.

B7-H3 (CD276 molecule) is an immune checkpoint from the B7 family of molecules that acts more as a co-inhibitory molecule to promote tumor progression. It is abnormally expressed on tumor cells and can be induced to express on antigen-presenting cells (APCs) including dendritic cells (DCs) and macrophages. In the tumor microenvironment (TME), B7-H3 promotes tumor progression by impairing T cell response, promoting the polarization of tumor-associated macrophages (TAMs) to M2, inhibiting the function of DCs, and promoting the migration and invasion of cancer-associated fibroblasts (CAFs). In addition, through non-immunological functions, B7-H3 promotes tumor cell proliferation, invasion, metastasis, resistance, angiogenesis, and metabolism, or in the form of exosomes to promote tumor progression. In this process, microRNAs can regulate the expression of B7-H3. B7-H3 may serve as a potential biomarker for tumor diagnosis and a marker of poor prognosis. Immunotherapy targeting B7-H3 and the combination of B7-H3 and other immune checkpoints have shown certain efficacy. In this review, we summarized the basic characteristics of B7-H3 and its mechanism to promote tumor progression by inducing immunosuppression and non-immunological functions, as well as the potential clinical applications of B7-H3 and immunotherapy based on B7-H3.

Keywords: B7-H3; Immunotherapy; MicroRNA; Tumor microenvironment; Tumor progression.

B7 homolog 3 (B7-H3) is a recently found superfamily B7 molecule and therefore has significant involvement in immunological regulation. However, the relationships of B7-H3 expression with the tumor microenvironment (TME), response to immunotherapy, and prognosis in head and neck squamous cell carcinoma (HNSCC) are still unknown. In the present analysis, we determined B7-H3 as a novel biomarker that predicts the prognosis and response to immunotherapy in HNSCC. B7-H3 expression is enhanced in HNSCC compared to normal sample and is stably expressed in HNSCC cell line. Besides, high B7-H3 expression is correlated with a dismal prognosis and resistance to immunotherapy and contributes to an immunosuppressive microenvironment. Moreover, single-cell RNA sequencing (scRNA-seq) analysis shows that B7-H3 is mainly expressed in the stromal as well as malignant cells. In conclusion, the study provides insight in understanding the prognostic value of B7-H3 in HNSCC and highlights its involvement in promoting the immunosuppressive microenvironment, which presents an attractive strategy for antibody-based immunotherapy.

Keywords: B7-H3; HNSCC; immune checkpoint; immunotherapy; prognostic biomarker.

Gastric cancer (GC), with a heterogeneous nature, is the third leading cause of death worldwide. Over the past few decades, stable reductions in the incidence of GC have been observed. However, due to the poor response to common treatments and late diagnosis, this cancer is still considered one of the lethal cancers. Emerging methods such as immunotherapy with immune checkpoint inhibitors (ICIs) have transformed the landscape of treatment for GC patients. There are presently eleven known members of the B7 family as immune checkpoint molecules: B7-1 (CD80), B7-2 (CD86), B7-H1 (PD-L1, CD274), B7-DC (PDCD1LG2, PD-L2, CD273), B7-H2 (B7RP1, ICOS-L, CD275), B7-H3 (CD276), B7-H4 (B7x, B7S1, Vtcn1), B7-H5 (VISTA, Gi24, DD1α, Dies1 SISP1), B7-H6 (NCR3LG1), B7-H7 (HHLA2), and Ig-like domain-containing receptor 2 (ILDR2). Interaction of the B7 family of immune-regulatory ligands with the corresponding receptors resulted in the induction and inhibition of T cell responses by sending co-stimulatory and co-inhibitory signals, respectively. Manipulation of the signals provided by the B7 family has significant potential in the management of GC.

Keywords: B7 family; gastric cancer; immune checkpoints; immunotherapy.

Background: Pyroptosis is a newly recognized form of cell death. Emerging evidence has suggested the crucial role of long non-coding RNAs (lncRNAs) in the tumorigenesis and progression of ovarian cancer (OC). However, there is still poor understanding of pyroptosis-related lncRNAs in OC. Methods: The TCGA database was accessed for gene expression and clinical data of 377 patients with OC. Two cohorts for training and validation were established by random allocation. Correlation analysis and Cox regression analysis were performed to identify pyroptosis-related lncRNAs and construct a risk model. Results: Six pyroptosis-related lncRNAs were included in the final signature with unfavorable survival data. Subsequent ROC curves showed promising predictive value of patient prognosis. Further multivariate regression analyses confirmed the signature as an independent risk factor in the training (HR: 2.242, 95% CI: 1.598-3.145) and validation (HR: 1.884, 95% CI: 1.204-2.95) cohorts. A signature-based nomogram was also established with a C-index of.684 (95% CI: 0.662-0.705). Involvement of the identified signature in multiple immune-related pathways was revealed by functional analysis. Moreover, the signature was also associated with higher expression of three immune checkpoints (PD-1, B7-H3, and VSIR), suggesting the potential of the signature as an indicator for OC immunotherapies. Conclusion: This study suggests that the identified pyroptosis-related lncRNA signature and signature-based nomogram may serve as methods for risk stratification of OC. The signature is also associated with the tumor immune microenvironment, potentially providing an indicator for patient selection of immunotherapy in OC.

Keywords: lncRNA; ovarian cancer; prognostic signature; pyroptosis; tumor immune microenvironment.

Background: There have been inconsistent results and conflicting conclusions among the existing prognostic studies of B7-H3 expression in colon cancer patients. Therefore, the association between B7-H3 expression and colon cancer survival has remained largely unclear.

Methods: We performed a three-phase and trans-ethnic prognostic study of B7-H3 expression in colon cancer patients involving perhaps the largest population to date. In the discovery phase, we utilized a Cox proportional hazards model adjusted for covariates to test the association between B7-H3 expression and colon cancer overall survival (OS) time in a European population from The Cancer Genome Atlas (TCGA) cohort (n=433). In the validation phase I, the association was replicated in a European population from Gene Expression Omnibus (GEO) cohort (n=811). In the validation phase II, we again confirmed the significant association in an Asian population from Fujian Medical University Union Hospital (UNION) cohort (n=179). Furthermore, a series of Kaplan-Meier analysis, bioinformatics analysis of tumor immune microenvironment (TIME), and immune checkpoint prognostic prediction analysis, as well as sensitivity analysis, were also conducted.

Results: Highly expressed B7-H3 was a significant and robust biomarker to colon cancer survival, with a large hazard ratio (HR) [HR_TCGA =4.60, 95% confidence interval (CI): 2.15 to 9.83, P=8.37×10^-05; HR_GEO =1.47, 95% CI: 1.12 to 1.94, P=0.0056; HR_UNION =1.63, 95% CI: 1.36 to 1.95, P=7.91×10^-08]. We detected an involvement of B7-H3 in the tumor immune microenvironment (TIME). Meanwhile, B7-H3 was significantly and weakly correlated with 6 out of 27 well-recognized immune checkpoint genes. Even after adjusting for effects of other immune checkpoint genes, B7-H3 still exhibited a harmful effect on colon cancer survival using samples from TCGA and GEO cohorts (HR =1.47, 95% CI: 1.07 to 2.02, P=0.0184), indicating that it was an independent prognostic factor of colon cancer. We also proposed an immune checkpoint prognostic risk score which possessed the capability to identify colon cancers with high risk of mortality.

Conclusions: The expression of B7-H3 is a significant, robust, and independent prognostic factor to colon cancer OS.

Keywords: B7-H3; colon cancer; gene expression; overall survival; prognostic factor.

Background: MicroRNAs play an important role in T cell responses. However, how microRNAs regulate Th cells in asthma remains poorly defined.

Objective: In this study, we investigated the mechanism and pathways of miR-29b regulating Th cells in asthma, in order to find new targets for asthma.

Methods: We detected miR-29b, B7-H3 and STAT3 in the peripheral blood of children with asthma, explored the relationship between these molecules and their effects on T cells through in vitro cell culture, and verified it by animal model.

Results: MiR-29b levels were decreased in the peripheral blood mononuclear cells from children with asthma. Vitro studies found that the expression of miR-29b in macrophages was decreased and the expression of B7-H3 and STAT3 was increased after house dust mite (HDM) stimulation. After down-regulation of miR-29b in macrophages, the expressions of B7-H3 and STAT3 in macrophages were increased and T cells differentiate into Th2 cells. After the addition of B7-H3 or STAT3 antibodies, the differentiation of naive T cells into Th2 cells was reduced. In OVA induced mice asthmatic model, after the up-regulation of miR-29b in lung, the expression of B7-H3 and STAT3 decreased in the lung tissues of mice, and the expression of Th2 cells and type II cytokine decreased simultaneously. The pathological changes of lung tissues were also alleviated.

Conclusion: The expression of miR-29b is decreased in asthmatic children. MiR-29b can inhibit Th2 cell differentiation by inhibiting B7-H3 and STAT3 pathways at the same time, and reduce asthmatic immune inflammation.

Keywords: B7‐H3; STAT3; Th2 cell; asthma; macrophages; miR‐29b.

Epithelial‑mesenchymal transition (EMT) is a key step in cancer metastasis. B7‑H3, a co‑signaling molecule associated with poor prognosis of non‑small cell lung cancer (NSCLC), promotes the metastasis of NSCLC by activating the EMT process. However, its underlying mechanism remains poorly understood. In the present study, it was shown that CRISPR/Cas9‑mediated B7‑H3 deletion downregulated the expression of the class III histone deacetylase, sirtuin‑1 (SIRT1), in NSCLC A549 cells. Accordingly, SIRT1 silencing resulted in markedly decreased migration and invasion of A549 cells. Both B7‑H3 gene‑edited and SIRT1‑silenced cells were typically characterized by an increased expression of the epithelial marker E‑cadherin, and downregulation of the mesenchymal markers N‑cadherin and vimentin, as compared with mock‑edited and scrambled negative small interfering RNA control, respectively. It was further demonstrated that B7‑H3 ablation significantly downregulated phosphorylated AKT/protein kinase B expression, and SIRT1 expression was substantially suppressed by the PI3K‑specific inhibitor, LY294002. Taken together, the findings of the present study revealed that B7‑H3‑induced signaling upregulates SIRT1 expression via the PI3K/AKT pathway to promote EMT activation that is associated with metastasis in NSCLC.

Keywords: B7‑H3; NSCLC; epithelial‑mesenchymal transition; invasion; migration.

B7-H3 is overexpressed in various solid tumors and has been considered as an attractive target for cancer therapy. Here, we report the development of DS-7300a, a novel B7-H3-targeting antibody-drug conjugate with a potent DNA topoisomerase I inhibitor, and its in vitro profile, pharmacokinetic profiles, safety profiles, and in vivo antitumor activities in nonclinical species. The target specificity and species cross-reactivity of DS-7300a were assessed. Its pharmacological activities were evaluated in several human cancer cell lines in vitro and xenograft mouse models including patient-derived xenograft (PDX) mouse models in vivo. Pharmacokinetics was investigated in cynomolgus monkeys. Safety profiles in rats and cynomolgus monkeys were also assessed. DS-7300a specifically bound to B7-H3 and inhibited the growth of B7-H3-expressing cancer cells, but not that of B7-H3-negative cancer cells, in vitro. Additionally, treatment with DS-7300a and DXd induced phosphorylated checkpoint kinase 1, a DNA damage marker, and cleaved poly (ADP-ribose) polymerase, an apoptosis marker, in cancer cells. Moreover, DS-7300a demonstrated potent in vivo antitumor activities in high-B7-H3 tumor xenograft models, including various tumor types of high-B7-H3 PDX models. Furthermore, DS-7300a was stable in circulation with acceptable pharmacokinetic profiles in monkeys, and well tolerated in rats and monkeys. DS-7300a exerted potent antitumor activities against B7-H3-expressing tumors in in vitro and in vivo models including PDX mouse models and showed acceptable pharmacokinetic and safety profiles in nonclinical species. Therefore, DS-7300a may be effective in treating patients with B7-H3-expressing solid tumors in a clinical setting.

Background: Patient-derived xenograft (PDX) models are biologically stable and can accurately reflect the primary tumor in histopathology and genetic expression in many cancers. In lung cancer, the models' engraftment rate by endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) and computed tomography (CT)-guided biopsy is exceptionally low, and this limits the development of PDX models in lung cancer research. In this study, we aimed to improve the traditional method, and explore the feasibility and convenience of establishing lung cancer PDX models using the samples directly from surgical resection. We also endeavored to explore the correlation between PDX formation and primary tumor B7-H3 protein expression.

Methods: From September 2017 to July 2018, 24 patients were enrolled in this study. The pathological diagnoses were as follows: 15 adenocarcinomas, 7 squamous cell carcinomas, 1 large cell carcinoma, and 1 small cell carcinoma. The tumor tissues were cut into sizes of 2×2×2 mm³/fragment and inoculated subcutaneously into immunodeficiency mice with a trocar needle. The engrafted tumors were passaged at least 3 generations, and B7-H3 IHC staining was performed on primary tumors. To explore the correlation between PDX formation and B7-H3 protein expression, we also performed H&E staining to evaluate whether the established PDX models could retain the histological features of the primary tumor.

Results: Xenograft formation success was achieved in 19 out of 24 cases (79.2%). The time between implantation to tumor formation was an average of 81.5 days (27-154 days) in P1, an average of 44.4 days (14-122 days) in P2, and an average of 26.9 days (12-75 days) in P3. The diameter of the tumor was associated with tumor engraftment: the longer the diameter, the easier engraftment formation was (P=0.0342). The data also suggests that lung cancers with B7-H3 expression greatly induced PDX formation (P=0.0375). The histological characters of each passage resembled the primary tumors.

Conclusions: This study shows that the samples from carefully selected lung cancer by surgical resection can be used for the establishment of PDX models with a high success rate; this improved method is closer to actual clinical work. Compared with the same kind of research, the success rate of the xenograft indicates significant improvement, so this improved method is suitable for promotion and application. The results of H&E staining showed that the histological characters of each passage resembled the primary tumors. Furthermore, the diameter of the tumor was associated with tumor engraftment, and higher B7-H3 expression demonstrated a statistically significant difference compared with the PDX model formation.

Keywords: B7-H3; non-small cell lung cancer (NSCLC); patient-derived tumor xenograft (PDX); pre-clinical model.